A GPS (Global Positioning System) is a system for specifying a position on the Earth. The GPS is effective when the position of an outdoor mobile body is specified in the order of several meters, for example, when a user drives an automobile on a road. A car navigation system specifies the present position of the user (the automobile) using the GPS and guides the user to a destination.
For example, Patent Literature 1 discloses a shopping guidance information providing apparatus that searches for a store present within a fixed distance from a terminal position and selling a registered purchase planned commodity and, when the store selling the purchase planned commodity is found near a user, informs, for guidance, a mobile terminal held by the user of information concerning the store.
However, in an indoor environment such as the inside of a building, in some case, a GPS signal is blocked by a roof or a wall and cannot be received. In some case, the GPS signal cannot be directly received behind a building and the GPS signal arriving bypassing the building is received to specify the present position. In this case, detection accuracy of the present position is sometimes deteriorated by the influence of the GPS signal arriving bypassing the building. In the conventional GPS, the present position cannot be specified in the order of 10 centimeters to 1 meter. Therefore, there is a problem in that it is difficult to specify the present position of a user in an indoor environment such as the inside of a store and guide the user to the position of a predetermined commodity.